1. Field of the Invention
The present invention relates to a method for monitoring the condition of at least one filter arranged in a flow path of a ventilator.
The present invention also relates to a device for monitoring the condition of at least one filter in a flow path of a ventilator, and to a ventilator containing such a device.
2. Description of the Prior Art
Filters of various kinds are frequently used in ventilators. In respiratory treatment, for example, bacterial filters are often employed to reduce the risk of a spread of infection between patients when the ventilator is connected to a new patient. Bacterial filters can also be used to reduce the risk of exposing patients to bacteria carried in inspiratory air and the escape of bacteria in expiratory air into ambient air. Bacterial filters can also be used to protect equipment from "contaminants", such as medication and body fluids, in expiratory air.
The use of disposable filters, which are discarded after each use and replaced with new filters when a new patient is to be connected to the ventilator, is relatively common. Disposable filters represent a major cost to hospitals and also have an environmental impact. Bacterial filters are available which can be autoclaved and, accordingly, used for a number of patients, with inter-patient autoclaving to disinfect the filter. The disadvantage of reusing a filter, however, is that it ultimately becomes clogged, thereby increasing resistance to flow in flow lines. A clogged filter can also increase pressure in the lungs of the patient connected to the ventilator and thus increase the risk of injury. Filter leakage after the filter has been autoclaved a number of times is an additional risk. Therefore, these filters are often discarded, while still fully serviceable, for safety reasons and are therefore not put to optimum use.
Disposable filters can naturally leak or become clogged as well, especially after a long period of use.